You know what? 1080p60 is not even really on my list of Things I Want Most From Forza, and I am a PC gamer at heart with years of time spent gaming almost entirely at 1080p60.
There are many other parts of Forza 5 that could make or break it as the front-runner launch game for the Xbox One. Will a new racing wheel be announced? Will it work with the very expensive previous Forza-branded wheels made for the 360 that were released less than two years ago? Will it have a day/night cycle? Weather? What's the track selection like? Will the Top Gear cooperation go even deeper? What's the career mode going to look like? What solutions will Turn 10 have for the years' worth of problems we've had in online races as far as lag, jumpy cars, or multiple car pile-ups in the first corner? Will we finally be able to make liveries using something other than a frigging gamepad?
As far as 1080p60 goes, that's not even a good measure of whether Turn 10 have had to scale things back to "fit" on the Xbox One. Of course they've had to scale things back. All racing games do, and nearly all other games do - of course Sony and MS are pulling your chain with that bullshit talk of seemingly limitless power. As far as Forza 5 goes, car models' poly counts can go into the millions - each - and then must be reduced, road scans' resolution must be downscaled to fit, even with 8GB of memory, and the coders could have always put more light and shadow passes and crazy effects in to the game to the point that they'd challenge even a pair of GTX Titans.
Stop thinking that Forza 5 is going to be the show of how limited or shitty or broken the Xbox One is because all hardware is limited and no single measure (like screen resolution) or even two measures (resolution + frame rate) will really tell you about the power of the console. Until there's a live demo running on real hardware where you can actually *see* what compromises they had to make, all sitting alongside important information like native resolution and frame rate, you won't know much about the performance anyway. And even if everything looks amazing, there are still huge pitfalls that hopefully Turn 10 avoided. After all, a good looking but rushed and empty-feeling racing game is not going to be a good front-running launch game.